Heretofore, 1,4-bis(aminomethyl)cyclohexane has been well known for a raw material of polyamide used for fiber, film, etc. Also, 1,4-bis(isocyanatomethyl)cyclohexane derived from 1,4-bis(aminomethyl)cyclohexane is useful as a raw material of polyurethane used for, for example, paints, adhesives, plastic lenses, etc.
Such 1,4-bis(aminomethyl)cyclohexane includes two types of stereo isomers, i.e., trans-1,4-bis(aminomethyl)cyclohexane (hereinafter may be referred to as trans isomer) and cis-1,4-bis(aminomethyl)cyclohexane (hereinafter may be referred to as cis isomer), and it has been known that the ratio of the cis isomer to the trans isomer in 1,4-bis(aminomethyl)cyclohexane affects various physical properties of polyamide or polyurethane produced by using the 1,4-bis(aminomethyl)cyclohexane.
For example, in the case of polyamide, the higher the ratio of the trans isomer in the raw material 1,4-bis(aminomethyl)cyclohexane is, the better the physical properties of melting point or thermal stability are, allowing production of polyamide suitable for fiber, film, etc.
In the case of polyurethane, by using, as a raw material, 1,4-bis(isocyanatomethyl)cyclohexane derived from 1,4-bis(aminomethyl)cyclohexane having a high ratio of trans isomer, polyurethane with excellent heat resistance and solubility in a solvent can be obtained.
Thus, in various industrial fields, a method for producing 1,4-bis(aminomethyl)cyclohexane having a high ratio of trans isomer has been desired.
As methods for producing 1,4-bis(aminomethyl)cyclohexane having a high ratio of trans isomer, for example, the following has been known: performing nuclear hydrogenation (addition of hydrogen to aromatic rings) of p-xylylenediamine in the presence of a ruthenium catalyst or a rhodium catalyst to produce 1,4-bis(aminomethyl)cyclohexane containing the cis isomer and the trans isomer; heating the 1,4-bis(aminomethyl)cyclohexane containing the cis isomer and the trans isomer in the presence of a platinum group catalyst to isomerize the cis isomer to the trans isomer; and thereafter, separating and recovering the 1,4-bis(aminomethyl)cyclohexane having a high trans isomer ratio from the isomerized solution, for example, by distillation (Patent Document 1) or by crystallization (Patent Document 2).
For a method for producing p-xylylenediamine used in the above-described method, for example, Patent Document 3 has proposed ammoxidation of p-xylene using a metal oxide catalyst such as vanadium to produce terephthalonitrile, and hydrogenating the terephthalonitrile in the presence of a nickel catalyst.
Furthermore, as a method for producing trans-1,4-bis(aminomethyl)cyclohexane, for example, Non-Patent Document 1 (Malachowski et al.) discloses the following: trans-1,4-cyclohexanedicarboxylic acid is allowed to react with thionyl chloride and followed by the reaction with ammonia to produce trans-1,4-cyclohexanedicarboxamide via acid chloride; and the trans-1,4-cyclohexanedicarboxamide is further allowed to react with thionyl chloride to obtain trans-1,4-dicyanocyclohexane, and then the obtained trans-1,4-dicyanocyclohexane is hydrogenated to produce trans-1,4-bis(aminomethyl)cyclohexane.